In 1994 we focused upon analysis of cellular connections in the visual cortex serving each eye. Axon terminals driven by the left and right eyes are not randomly distributed in the primary visual cortex, but organized into a mosaic of alternating stripes called "ocular dominance columns" (ODC). We developed a method to label ODC in human tissues obtained at autopsy. We are presently mapping the arrangement of ODC in the visual cortex of normal monkeys and humans, and studying the development of ODC in young animals and babies. In 1994, we demonstrated that ODC are well developed in newborn rhesus, prior to light exposure or visual experience. This indicates that the columnar architecture of the cerebral cortex forms innately, without need for environmental stimulation. In monkeys, monocular eyelid suture induces amblyopia by depriving the retina of patterned stimulation, just as a unilateral cataract produces amblyopia in a child. We are using this experimental model to study amblyopia in monkeys. We produce amblyopia by closing one eye in monkeys at various ages after birth. In normal monkeys and humans, the columns serving each eye are approximately equal in width. However, in monkeys rendered amblyopic by early eyelid suture, the odc serving the deprived eye appear abnormally thin and fragmented. This shrinkage of the ODC reduces the deprived eye's connections to the visual cortex. We are also investigating abnormalities in the organization of the visual cortex associated with other forms of amblyopia, such as those produced by strabismus or anisometropia. Finally, we are studying how visual deprivation affects the connections serving the deprived eye that link primary visual cortex with the rest of the visual cortex. We suspect that these experiments will reveal that a failure of information transfer between different visual cortical areas contributes to the loss of visual function in amblyopia.